Introduction

In this article I describe how to create a Windows Store App for storing data in a file in roaming folder using JavaScript. User data in an app can be stored as files. There are three locations available for storing files; they are:

  1. Windows.Storage.ApplicationData.current.localFolder
  2. Windows.Storage.ApplicationData.current.roamingFolder
  3. Windows.Storage.ApplicationData.current.temporaryFolder.
I assume you can create a simple Windows Store App using JavaScript. For more help visit Simple Windows Store Apps using JavaScript.

To start the creation of the app, add one JavaScript page by right-clicking on the js folder in the Solution Explorer and select Add > new item > JavaScript Page and then give an appropriate name. In the same way, add one HTML page to your project.

files-in-windows-store-apps.jpg

Write the following code in default.html:

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8" />

<title>App</title>

<link rel="stylesheet" href="//Microsoft.WinJS.1.0/css/ui-light.css" />

<script src="//Microsoft.WinJS.1.0/js/base.js"></script>

<script src="//Microsoft.WinJS.1.0/js/ui.js"></script>

<link rel="stylesheet" href="/css/default.css" />

<script src="/js/default.js"></script>

</head>

<body role="application" style="background-color: lightyellow">

<center><div id="rootGrid">

<div id="content">

<h1 id="featureLabel"></h1>

<div id="contentHost"></div>

</div>

</div></center>

</body>

</html>

Write the following code in default.js:

(function () {

"use strict";

var appTitle = "";

var pages = [

{ url: "page.html", title: "SetVersion" }

];

function activated(eventObject) {

if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {

eventObject.setPromise(WinJS.UI.processAll().then(function () {

var url = WinJS.Application.sessionState.lastUrl || pages[0].url;

return WinJS.Navigation.navigate(url);

}));

}

}

WinJS.Navigation.addEventListener("navigated", function (eventObject) {

var url = eventObject.detail.location;

var host = document.getElementById("contentHost");

host.winControl && host.winControl.unload && host.winControl.unload();

WinJS.Utilities.empty(host);

eventObject.detail.setPromise(WinJS.UI.Pages.render(url, host, eventObject.detail.state).then(function () {

WinJS.Application.sessionState.lastUrl = url;

}));

});

WinJS.Namespace.define("App", {

appTitle: appTitle,

pages: pages

});

WinJS.Application.addEventListener("activated", activated, false);

WinJS.Application.start();

})();

Write the following code in page.html:

<!DOCTYPE html>

<html>

<head>

<title></title>

<link rel="stylesheet" href="/css/default.css" />

<script src="/js/script.js"></script>

</head>

<body>

<div data-win-control="App.pageInput">

<button class="action" id="filesIncrement">Create File</button>

</div>

<div data-win-control="App.pageOutput">

<div class="item" id="filesOutput"></div>

</div>

</body>

</html>


Write the following code in script.html:

(function () {

"use strict";

var page = WinJS.UI.Pages.define("page.html", {

ready: function (element, options) {

document.getElementById("filesIncrement").addEventListener("click", filesIncrement, false);

filesDisplayOutput();

}

});

var roamingFolder = Windows.Storage.ApplicationData.current.roamingFolder;

var filename = "appFile.txt";

var counter = 0;

function filesIncrement() {

counter = counter + 1;

roamingFolder.createFileAsync(filename, Windows.Storage.CreationCollisionOption.replaceExisting)

.then(function (file) {

return Windows.Storage.FileIO.writeTextAsync(file, counter);

}).done(function () {

filesDisplayOutput();

});

}

function filesReadCounter() {

roamingFolder.getFileAsync(filename)

.then(function (file) {

return Windows.Storage.FileIO.readTextAsync(file);

}).done(function (text) {

counter = parseInt(text);

document.getElementById("filesOutput").innerText = "file: " + counter;

}, function () {

document.getElementById("filesOutput").innerText = "file: <not found>";

});

}

function filesDisplayOutput() {

filesReadCounter();

}

})();


Output:

files-in-windows-store-app.jpg

Summary

In this app I described how to store data in a file in a roaming folder in a Windows Store App using JavaScript. I hope this article has helped you to understand this topic. Please share if you know more about this. Your feedback and constructive contributions are welcome.